diff --git a/hexrdgui/calibration/cartesian_plot.py b/hexrdgui/calibration/cartesian_plot.py
index 1b329e5d8..45548722d 100644
--- a/hexrdgui/calibration/cartesian_plot.py
+++ b/hexrdgui/calibration/cartesian_plot.py
@@ -22,6 +22,8 @@
 def cartesian_viewer():
     return InstrumentViewer()
 
+def get_xray_propagation_sign(instr):
+    return np.sign(instr.beam_vector[2])
 
 class InstrumentViewer:
 
@@ -29,6 +31,10 @@ def __init__(self):
         self.type = ViewType.cartesian
         self.instr = create_hedm_instrument()
         self.images_dict = HexrdConfig().images_dict
+
+        # Set invalid pixels to be nan
+        HexrdConfig().apply_panel_buffer_to_images(self.images_dict)
+
         self.img = None
 
         # Perform some checks before proceeding
@@ -40,7 +46,8 @@ def __init__(self):
         self.detector_corners = {}
 
         dist = HexrdConfig().cartesian_virtual_plane_distance
-        dplane_tvec = np.array([0., 0., -dist])
+        sgn = get_xray_propagation_sign(self.instr)
+        dplane_tvec = np.array([0., 0., sgn*dist])
 
         rotate_x = HexrdConfig().cartesian_plane_normal_rotate_x
         rotate_y = HexrdConfig().cartesian_plane_normal_rotate_y
@@ -280,8 +287,15 @@ def create_warped_image(self, detector_id):
 
         res = tf.warp(img, tform3,
                       output_shape=(self.dpanel.rows, self.dpanel.cols),
-                      preserve_range=True)
-        self.warp_dict[detector_id] = res
+                      preserve_range=True, cval=np.nan)
+        nan_mask = np.isnan(res)
+
+        self.warp_dict[detector_id] = np.ma.masked_array(
+            res,
+            mask=nan_mask,
+            fill_value=0,
+        )
+
         return res
 
     @property
@@ -290,8 +304,15 @@ def display_img(self):
 
     def generate_image(self):
         img = np.zeros((self.dpanel.rows, self.dpanel.cols))
+        always_nan = np.ones(img.shape, dtype=bool)
         for key in self.images_dict.keys():
-            img += self.warp_dict[key]
+            # Use zeros when summing, but identify pixels that
+            # are nans in all images and set those to nan.
+            warp_img = self.warp_dict[key]
+            img += warp_img.filled(0)
+            always_nan = np.logical_and(always_nan, warp_img.mask)
+
+        img[always_nan] = np.nan
 
         # In case there were any nans...
         nan_mask = np.isnan(img)
diff --git a/hexrdgui/hexrd_config.py b/hexrdgui/hexrd_config.py
index 8f8afe5b4..2ba5c2b5f 100644
--- a/hexrdgui/hexrd_config.py
+++ b/hexrdgui/hexrd_config.py
@@ -535,6 +535,12 @@ def load_from_state(self, state):
                 pinhole_settings.pop('pinhole_radius') * 2
             )
 
+        if self.cartesian_virtual_plane_distance < 0:
+            # We used to allow this to be negative, but now must be positive.
+            # Taking the absolute value should correct this adequately.
+            self.cartesian_virtual_plane_distance = abs(
+                self.cartesian_virtual_plane_distance)
+
         # All QSettings come back as strings. So check that we are dealing with
         # a boolean and convert if necessary
         if not isinstance(self.live_update, bool):
@@ -2511,7 +2517,8 @@ def _cartesian_pixel_size(self):
     def _set_cartesian_pixel_size(self, v):
         if v != self.cartesian_pixel_size:
             self.config['image']['cartesian']['pixel_size'] = v
-            self.rerender_needed.emit()
+            if self.image_mode == constants.ViewType.cartesian:
+                self.rerender_needed.emit()
 
     cartesian_pixel_size = property(_cartesian_pixel_size,
                                     _set_cartesian_pixel_size)
@@ -2520,9 +2527,13 @@ def _cartesian_virtual_plane_distance(self):
         return self.config['image']['cartesian']['virtual_plane_distance']
 
     def set_cartesian_virtual_plane_distance(self, v):
+        if v < 0:
+            raise RuntimeError(f'Invalid plane distance: {v}')
+
         if v != self.cartesian_virtual_plane_distance:
             self.config['image']['cartesian']['virtual_plane_distance'] = v
-            self.rerender_needed.emit()
+            if self.image_mode == constants.ViewType.cartesian:
+                self.rerender_needed.emit()
 
     cartesian_virtual_plane_distance = property(
         _cartesian_virtual_plane_distance,
@@ -2534,7 +2545,8 @@ def _cartesian_plane_normal_rotate_x(self):
     def set_cartesian_plane_normal_rotate_x(self, v):
         if v != self.cartesian_plane_normal_rotate_x:
             self.config['image']['cartesian']['plane_normal_rotate_x'] = v
-            self.rerender_needed.emit()
+            if self.image_mode == constants.ViewType.cartesian:
+                self.rerender_needed.emit()
 
     cartesian_plane_normal_rotate_x = property(
         _cartesian_plane_normal_rotate_x,
@@ -2546,7 +2558,8 @@ def _cartesian_plane_normal_rotate_y(self):
     def set_cartesian_plane_normal_rotate_y(self, v):
         if v != self.cartesian_plane_normal_rotate_y:
             self.config['image']['cartesian']['plane_normal_rotate_y'] = v
-            self.rerender_needed.emit()
+            if self.image_mode == constants.ViewType.cartesian:
+                self.rerender_needed.emit()
 
     cartesian_plane_normal_rotate_y = property(
         _cartesian_plane_normal_rotate_y,
diff --git a/hexrdgui/image_mode_widget.py b/hexrdgui/image_mode_widget.py
index 6fa540285..cf1f833c3 100644
--- a/hexrdgui/image_mode_widget.py
+++ b/hexrdgui/image_mode_widget.py
@@ -40,6 +40,9 @@ def __init__(self, parent=None):
         # Always start with raw tab
         self.ui.tab_widget.setCurrentIndex(0)
 
+        # Don't allow negative distances
+        self.ui.cartesian_virtual_plane_distance.setMinimum(1e-8)
+
         # Hide stereo_project_from_polar for now, as projecting from polar
         # appears to give a better image (lines up better with overlays)
         # than projecting from raw.
diff --git a/hexrdgui/resources/ui/image_mode_widget.ui b/hexrdgui/resources/ui/image_mode_widget.ui
index fa96859e7..051cb5f0f 100644
--- a/hexrdgui/resources/ui/image_mode_widget.ui
+++ b/hexrdgui/resources/ui/image_mode_widget.ui
@@ -38,7 +38,7 @@
       <enum>QTabWidget::Rounded</enum>
      </property>
      <property name="currentIndex">
-      <number>2</number>
+      <number>1</number>
      </property>
      <property name="iconSize">
       <size>
@@ -167,6 +167,9 @@
               <property name="decimals">
                <number>8</number>
               </property>
+              <property name="minimum">
+               <double>0.000000000000000</double>
+              </property>
               <property name="maximum">
                <double>1000000.000000000000000</double>
               </property>